1. Field of the Invention
The present invention relates to a centrifugal master clutch and a vehicular transmission system utilizing the same. In particular, the present invention relates to an automated vehicular transmission system comprising an engine, a multiple ratio transmission, a centrifugally operated master friction clutch for drivingly coupling the engine to the transmission and a controller for controlling fueling of the engine during vehicle launch conditions, as a function of throttle position and other sensed system operating conditions such as at least one of engine speed, transmission input shaft speed, transmission output shaft speed, engine torque and engaged gear ratio.
More particularly, an exemplary embodiment of the present invention relates to a start control method/system for a vehicular automated mechanical transmission system utilizing a centrifugal master friction clutch controlled solely by engine speed and a controller for controlling engine fueling during vehicle launch conditions.
2. Description of the Prior Art
Automated mechanical transmission systems not requiring the vehicle driver or operator to operate the vehicle master clutch (so called xe2x80x9ctwo-pedal systemsxe2x80x9d), and clutch controls and actuators therefore, are known in the prior art as may be seen by reference to U.S. Pat. Nos.: 4,081,065; 4,361,060; 4,936,428; 5,439,428; 5,634,867; 5,630,773; 5,960,916 and; 5,947,847, the disclosures of which are incorporated herein by reference. These systems are not totally satisfactory as separate clutch actuators, sensors and/or, electrical and/or fluid power (i.e., compressed and/or hydraulic) connections thereto are required which adds to the expense of providing, assembling and maintaining such systems.
Centrifugally operated friction clutches are well known in the prior art and typically include a driving input member driven by a prime mover, usually an electric motor or internal combustion engine, and weights rotatable with the driving member which, upon rotation of the driving member, will move radially outwardly under the effect of centrifugal force to cause the driving input member to frictionally engage a driven output member. Examples of centrifugally operated clutches may be seen by reference to U.S. Pat. Nos.: 3,580,372; 3,696,901; 5,437,356; 3,810,533; 4,819,779; 5,441,137; 5,730,269; and; 4,610,343, the disclosures of which are incorporated herein by reference.
Fully or partially automated mechanical transmission systems that, upon determining that a dynamic shift from a currently engaged ratio into neutral and then into a target ratio is desirable, will, while maintaining the vehicle master friction clutch engaged, initiate automatic fuel control to cause reduced torque across the jaw clutches to be disengaged, are known in the prior art as may be seen by reference to U.S. Pat. Nos.: 4,850,236; 5,820,104; 5,582,558; 5,735,771; 5,775,639; 6,015,366; and 6,126,570, the disclosures of which are incorporated herein by reference. These systems include systems that attempt to fuel the engine to achieve a sustained zero driveline torque, and systems which force torque reversals, see U.S. Pat. No.: 4,850,236. These systems, upon sensing a neutral condition, will, while maintaining the master clutch engaged, cause the engine to rotate at a speed determined to cause synchronous conditions for engaging the target ratio.
Vehicular driveline systems, especially for heavy-duty vehicles, utilizing centrifugal clutches have not been satisfactory as the engines were typically controlled by throttle device position, not on a closed loop basis based upon a target engine speed and/or engine torque, and thus did not provide acceptable control for smooth vehicle launch and low speed operation. Prior art vehicular driveline systems utilizing centrifugal master clutches where not provided with clutches having damage and/or overheating protection and/or were not configured to lock up and release at engine speeds selected to permit dynamic shifting with the master clutch engaged.
Centrifugal clutches are engaged and disengage as a function of engine speed, requiring manipulation of engine speed to selectively engage and disengage the clutch. The need to manipulate the engine speed to achieve engagement and disengagement can make it difficult to overcome certain conditions, and in particular a tooth-butt condition. The tooth butt condition may occur when attempting to shift into gear with the vehicle stopped. The teeth of an engaging clutch sleeve hits or butts against the end of the intended receiving splines of the gear targeted for engagement. With no relative rotation between the parts, they remain butted against each other. With a conventional manually controlled master clutch, the master clutch would be momentarily engaged to spin up the input shaft and momentarily produce relative rotation between the sleeve and the target gear. With a centrifugal clutch, one lacks the ability to manually engage the master clutch to provide the desired relative rotation between the clutch sleeve and the gear.
In accordance with the present invention, the drawbacks of the prior art are reduced or minimized by the provision of a centrifugal master friction clutch, and a vehicular automated transmission system utilizing the same, which utilizes closed loop control to encourage engagement by using the controller to vary the engine speed.
A method for controlling a vehicular automated transmission system to overcome a tooth butt condition is disclosed herein. The automated transmission system includes an internal combustion engine having an engine output member, a multiple speed change gear transmission having an input shaft, a centrifugal friction clutch for drivingly connecting said engine output member to said input shaft, a throttle responsive to manually requesting of a degree of engine fueling, and a system controller. The system controller receives input signals including two or more of signals of (i) engine speed, (ii) throttle position, (iii) engaged transmission ratio, (iv) input shaft speed, (v) vehicle speed, (vi) a position of jaw clutch members, and (vii) shift signals indicative of attempting to shift the transmission into gear. The system controller has at least one mode of operation for selectively controlling engine fueling to control at least one of engine speed and engine torque. The system controller processes said signals according to logic rules to issue command output signals to system actuators including at least said engine controller. The method includes the steps of:
(a) sensing certain tooth butt constituent conditions;
(b) establishing the occurrence of the tooth butt condition based on the tooth butt constituent conditions;
c) imposing automatic control of the engine by the controller with the occurrence of the tooth butt condition;
d) at least periodically checking the tooth butt constituent conditions after the occurrence of the tooth butt condition and ending automatic control of the engine by the controller if any of the tooth butt constituent conditions are not satisfied;
e) automatically increasing the engine speed at a first ramp-rate under control of the controller until one of a first target engine speed and a first target elapsed ramp-up time is reached;
f) automatically decreasing the engine speed to an idle speed upon reaching one of the first target engine speed and the first target elapsed ramp-up time under control of the controller;
g) if the transmission remains in a tooth butt condition after reducing the engine speed to idle, again automatically increasing the engine speed under control of the controller at a second ramp-rate up to a maximum established by one of a second target engine speed and a second target elapsed ramp-up time;
h) automatically decreasing the engine speed to an idle speed upon reaching one of the second target engine speed and the second target elapsed ramp-up time under control of the controller; and
i) releasing automatic control of the engine by the controller.
A method for controlling a vehicular automated transmission system to overcome a tooth butt condition is disclosed herein. The automated transmission system includes an internal combustion engine having an engine output member, a multiple speed change gear transmission having an input shaft, a centrifugal friction clutch for drivingly connecting said engine output member to said input shaft, a throttle responsive to manually requesting of a degree of engine fueling, and a system controller. The system controller receives input signals including two or more of signals of (i) engine speed, (ii) throttle position, (iii) engage transmission ratio, (iv) input shaft speed, (v) vehicle speed, (vi) a position of jaw clutch members, and (vii) shift signals indicative of attempting to shift the transmission into gear. The system controller has at least one mode of operation for selectively controlling engine fueling to control at least one of engine speed and engine torque. The system controller processes said signals according to logic rules to issue command output signals to system actuators including at least said engine controller. The method includes the steps of:
(a) sensing certain tooth butt constituent conditions;
(b) establishing the occurrence of the tooth butt condition based on the tooth butt constituent conditions;
c) transferring engine control to an anti-butt routine within the system controller with the occurrence of the tooth butt condition;
d) at least periodically checking the tooth butt constituent conditions during execution of the anti-butt routine and exiting the anti-butt routine if any of the tooth-butt constituent conditions are not satisfied;
e) automatically increasing the engine speed at a first ramp-rate under control of the anti-butt routine until one of a first target engine speed and a first target elapsed ramp-up time is reached;
f) automatically decreasing the engine speed to an idle speed upon reaching one of the first target engine speed and the first target elapsed ramp-up time under control of the anti-butt routine;
g) if the transmission remains in a tooth butt condition after reducing the engine speed to idle, again automatically increasing the engine speed under control of the anti-butt routine at a second ramp-rate up to a maximum established by one of a second target engine speed and a second target elapsed ramp-up time;
h) automatically decreasing the engine speed to an idle speed upon reaching one of the second target engine speed and the second target elapsed ramp-up time under control of the controller; and
i) releasing automatic control of the engine by the controller.
A control system for controlling a vehicular automated transmission system to overcome a tooth butt condition is disclosed herein. The automated transmission system includes an internal combustion engine having an engine output member, a multiple speed change gear transmission having an input shaft, a centrifugal friction clutch for drivingly connecting said engine output member to said input shaft, a throttle responsive to manually requesting of a degree of engine fueling, and a system controller. The system controller receives input signals including two or more of signals of (i) engine speed, (ii) throttle position, (iii) engaged transmission ratio, (iv) input shaft speed, (v) vehicle speed, (vi) a position of jaw clutch members, and (vii) shift signals indicative of attempting to shift the transmission into gear. The system controller has at least one mode of operation for selectively controlling engine fueling to control at least one of engine speed and engine torque. The system controller processes said signals according to logic rules to issue command output signals to system actuators including at least said engine controller. The control system includes logic steps effective for:
a) sensing certain tooth butt constituent conditions;
b) establishing the occurrence of the tooth butt condition based on the tooth butt constituent conditions;
c) imposing automatic control of the engine by the controller with the occurrence of the tooth butt condition;
d) at least periodically checking the tooth butt constituent conditions after the occurrence of the tooth butt condition and ending automatic control of the engine by the controller if any of the tooth butt constituent conditions are not satisfied;
e) automatically increasing the engine speed at a first ramp-rate under control of the controller until one of a first target engine speed and a first target elapsed ramp-up time is reached;
f) automatically decreasing the engine speed to an idle speed upon reaching one of the first target engine speed and the first target elapsed ramp-up time under control of the controller;
g) if the transmission remains in a tooth butt condition after reducing the engine speed to idle, again automatically increasing the engine speed under control of the controller at a second ramp-rate up to a maximum established by one of a second target engine speed and a second target elapsed ramp-up time;
h) automatically decreasing the engine speed to an idle speed upon reaching one of the second target engine speed and the second target elapsed ramp-up time under control of the controller; and
i) releasing automatic control of the engine by the controller.
These and other objects and advantages of the present invention will become apparent from a reading of the following description of the preferred embodiment taken in connection with the attached drawings.